How to get Entity at the servlet using MultipartEntity?

Question

If i Upload a file to my servlet like this:

HttpClient httpclient = new DefaultHttpClient();
HttpPost httppost = new HttpPost("http://www.tumblr.com/api/write");

try 
{
    MultipartEntity entity = new MultipartEntity();
    entity.addPart("type", new StringBody("photo"));
    entity.addPart("data", new FileBody(image));
    httppost.setEntity(entity);
    HttpResponse response = httpclient.execute(httppost);
} 
catch (ClientProtocolException e) {} 
catch (IOException e) {}

How can I retrieve the content at the servlet?

protected void doPost(HttpServletRequest request, HttpServletResponse response) throws  IOException 
{
     request.???
}

• I'm using Google App Server as my Servlet API

Answer 1

If the version of your Servlet Container or Server or Engine < 3.0 (like 2.5 or earlier) , you may want to take advantage of the third-party Library Apache Commons FileUpload. Although the file implied an use for uploaded Files, it also deals effectually with uploaded posted Data from POST-Methods like it explained here.

the Servlet API, from the version 3.0 offers some calls in oder to deal with posted Data, with was sent within a POST-Request. the only requirement is that the MIME-Type encoding of your entity content is "multipart/form-data".

then your can retrieve each "part" of your content using either:

1. getPart(String partName): where "partName" is the name of a part of your Multicontent entity.

   protected void doPost(HttpServletRequest request, HttpServletResponse response) throws  IOException 
   {
       String partName = "type"; // or "data"
       Part part = request.getPart(partName);
   
       // read your StringBody type
       BufferedReader reader = new BufferedReader( new InputStreamReader(part.getInputStream()));
       String line ="";
   
       while((line=reader.readLine())!=null)
       {
           // do Something with a line
           System.out.println(line);
   
       }
   
       // or with a binary Data
       partName="data";
       part = request.getPart(partName);
   
       // read your FileBody data
       InputStream is = part.getInputStream();
       // do Something with you byte data
   
       is.read();
       // is.read(b);
       // ..
   
   }
   

2. getParts():

it achieves the same results as getPart(partName), whereas the given data here a collection of all part of the sent data. to retrieve each par of the Part of this collection, just use thread-safe iteration over the collection:

Iterator<Part> iterator = request.getParts().iterator();
       Part parts = null;
       while (iterator.hasNext()) {
       parts = (Part) iterator.next();
          //rest of the code block removed
       }
    }

Because the getPart()/getParts() only works beginning at the Servlet 3.0 version, you'll make sure to use the supporting Servlet container and/or upgrade your current Servlet Container. some Server or Servlet container that supports 3.0:

1. tomcat 7.0:
2. Jboss Web
3. Resin